Method and system for the treatment of waste

ABSTRACT

In a method for treating waste products and recycling products of solid organic or inorganic materials or composite materials or mixtures thereof, a breaking-up or separation of the components by means of an impulse is effected in the composite material or the mixture by a device which suddenly interrupts the flow of said composite material or mixture. Process air is fed in a counter-rotating, rising flow path into the spiral-like downward transport path generated in a rotor having a vertical axis and a shockwave is generated between the layers of the composite material against a deflector wall of the rotor. In addition, two radially spaced, coaxially arranged wall faces rotate relatively to one another about their axis and the composite materials or mixtures moved by centrifugal forces are moved and broken up between deflector faces projecting radially from the deflector walls.

This application is a 371 of PCT/EP03/04510, filed Apr. 30, 2003(designating the U.S.; and which published in German in WO 03/103859 onDec. 18, 2003), which claims the benefit of German Patent ApplicationNo. 102 19 724.5, May 4, 2002, incorporated herein by reference.

TECHNICAL FIELD

The invention relates to a method and a device for treating wasteproducts and recycling products of solid organic or inorganic materials,or composite materials and mixtures thereof.

BACKGROUND

The above-mentioned waste products include, for example, industrialrecycling products such as electronic scrap or slags from metalsmelting, but also household waste of various compositions. The latterinclude primarily organic mixtures such as foodstuffs, plasticspackaging, composite packaging, as well as inorganic components such asglass, metals and composites thereof.

These mixtures and composite elements pose problems in particular duringdisposal, since separation of the mixtures and of the materialscontained in the composite has been carried out hitherto either not atall or only inadequately, with high consumption of energy. Most of thesewaste products are incinerated or dumped. Only waste products with lowimpurity content—for example cans of aluminium sheet—are subjected tomaterial recovery treatment. More complex waste is not subjected totreatment or material recovery through lack of technical possibilitiesor the high cost resulting, for example, from wet-chemical processes orthermal processes.

In the conventional mechanical processing procedure, the compositeelement is broken up by way of the grain or particle size which issmaller than the respective layer thickness of the components. Thisbreaking-up operation is generally effected by using an at leastone-stage very fine crushing operation using suitable mills—for example,hammer, impact or counter-flow mills—possibly with the assistance ofnitrogen for inerting and cooling purposes.

Known from FR-A-1 562 013 is a comminution mill comprising a rotorhaving a plurality of rotating discs and a cylindrical housingsurrounding said rotor, in which material to be milled is fed by a wormdevice to the lower end of the rotor and is then picked up by theairflow of a fan disposed across the rotor above a sieve base and belowthe rotor bearing. The upwardly-impelled milling product is comminutedby so-called plaques de broyage, i.e. milling or crushing plates, whichproject radially from rotating rotor plates and are arranged close tothe housing wall. The ends of the milling or crushing platesco-operating with the housing wall are in each case equipped withelliptical frames; these frames describe a constructed circle againstthe inner face of the housing and are claimed to assist the milling andcomminution effect. Moreover, in the view of the author of FR-A-1 562613, turbulences are additionally involved in this comminution process.A bypass which recirculates sieved-out coarse particles to the lowerintake leads off from the housing of this comminution mill below thefan.

A comminution mill of this kind is also disclosed by DE-A-42 13 274,which machine is used as a micro-fluidised-separator mill for finecomminution of composite materials containing metals, in particular forrecovering precious metals, from mounted circuit boards. The copper, forexample, is reduced to a grain size of approximately 80 to 100 μm andremoved via the separator air. Arranged at an opening of a bypass is adeflector edge which deflects the particles flowing at the periphery ofthe rotor into the bypass opening. The eddies produced by the rotarymotion of the rotor are illustrated in the drawings in the manner of acomic strip phenomenon, without explanation of their significance interms of process technology.

WO-A 9 305 883 contains a process flow diagram for recovering fibresfrom glassfibre-reinforced plastics or the like using a shredder, afterwhich the shredded product is pulverised. Liberated fibres are separatedfrom this powder and the remaining pulverised waste is used, forexample, as filler. This process diagram contains a micro-mill referredto as a pulveriser which resembles that from FR-A-1 562 013 inconstruction.

In a process according to WO 95/25595 for treating composite elements ofsolid organic and/or inorganic composite materials such as composites ofmetal/metal, plastic/plastic, metal/plastic or mineral composites withmetals and/or plastic materials, a mixture is fed to the flow-breakawayedges with an acceleration of 20 to 60 m/sec² and a movement isestablished in the eddies which acceleratingly breaks up a mixture. Inaddition, during this separation or breaking-up procedure the adhesionbetween the components of the solid particles is overcome byacceleration and frictional forces which exceed the adhesion force, andthe components of the solid particles are detached or removed from oneanother, the layers of the above-mentioned composite material beingseparated.

The known methods therefore have the object of processing, comminuting,homogenising and partially or wholly separating composite materials andmixtures of materials. Such methods are based in particular onmechanical shearing and crushing, on relatively uncontrolledfragmentation or separation in high-energy eddies.

OVERVIEW

In awareness of these factors it is the object of the invention todevelop a method whereby mixtures and composite elements are treated insuch a way that the fractions recovered from the process can be fed backas valuable substances into the economic cycles.

This object is achieved by the teaching of the independent claim; thedependent claims specify advantageous refinements. In addition, allcombinations of at least two of the features disclosed in thedescription, the drawings and/or the claims fall within the scope of theinvention.

According to the invention the mixtures and composite materials arebroken up and separated by means of a mechanical procedure in which theimpulse generated by the sudden arresting of a transported particle isutilised. In the composite material or the mixture a breaking-up orseparation of the components is effected by a device which suddenlyinterrupts the flow of said composite material or mixture, by means ofan impulse; in and between the layers of the composite elementsshockwaves are produced which break up these composite elements. Forthis purpose it has proved advantageous for process air to be directedin a counter-rotating rising flow path into the spiral-like downwardtransport path generated in a rotor having a vertical axis; theabove-mentioned shockwave is preferably generated between the layers ofthe composite material against a deflector wall of the rotor.

According to a further feature of the invention two wall faces coaxiallyarranged at a radial distance from one another rotate relatively to oneanother about their axis, and the composite materials or mixtures movedby centrifugal forces are moved and broken up between deflector facesprojecting radially from the deflector walls. The breaking-up of thecomposite can occur on impact against a deflector wall and its metalcomponents are deformed spherically; during the deformation process thelayer-like metal component is preferably rolled up.

It has proved advantageous to disintegrate the composite element to aparticle size of 10 mm to 50 mm before the separation and breaking-upprocess and optionally also to subject it to thermal pretreatment. Inaddition, the material discharged from the separation or breaking-upprocess can advantageously be subjected to a separation and/or siftingprocess or a process for separating non-ferrous metals.

According to a further feature of the invention the separation iscarried out on separator tables and/or by fluidised bed separators, themetal and/or plastics parts being compacted after separation. For thispurpose it is advantageous to separate the plastics from one another byturbo-laminar separation and identification and/or to extrude the metaland/or plastics constituents after separation.

Based on inherent material properties—such as density, modulus ofelasticity (=stiffness=resistance to deformation), strength andmolecular constellation—shockwaves generated according to the inventionare disseminated within the materials and have different configurationsregarding their propagation velocity, frequency and amplitude. If theforces generated by these shockwaves on impact of the particles exceedthe adhesion force of the interfaces—the contact faces between theindividual material phases—the resulting micro-shearing leads todetachment or separation. This principle is utilised in a specified andintentional manner according to the invention.

The typical flow behaviour when elastic extension, e.g. for metals, orinherent elasticity, e.g. of plastics, is exceeded results in permanentspherical deformations or in partial elastic restoration of the originalparticle shape (resilience). As a result of this phenomenon thephase-separated elements of composite materials can be relatively easilysorted using known and established technologies—e.g. on a mechanical,hydraulic or pneumatic basis.

The method described is distinguished by the simplicity andfunctionality of the device according to the invention, resulting incorrespondingly simple and unproblematic operation. The intendedsimplicity of the concept and construction of the rotor machinedescribed permits its technical realisation without difficulty. Theutilisation of knowledge from materials science, of heat treatmentprocesses, of computer- and simulation-aided design optimisation, andthe possible adaptation and optimisation of process parameters willfurther increase the efficiency which can be anticipated.

A device for carrying out the method described, in which the transportpath for the composite materials or the mixture inside a rotor isdirected against the flow path of process air and in which the materialfeed device is arranged in the roof area of the rotor, falls within thescope of the invention. The transport path is to be disposed between tworelatively movable wall faces spaced at a distance, from which deflectorfaces offset with respect to one another project into the transport pathfrom both sides.

According to further features of the invention the wall faces arecoaxially curved and/or are journalled rotatably in the direction ofrotation of the rotor.

Because of the simplicity of the core process and of the separator, andbecause of the large throughput performance which is apparent, theresulting costs of separation should actually be relatively low. Thecorresponding costs represent ultimately the total consumption ofresources such as transport, energy and labour requirements (alwaysassociated with the consumption of resources!), water-air and landconsumption, the substitution effect and the like, and consequently theentire environmental impact. If the quantity of successfully treatedflows of waste and their conversion into flows of useful materialsincreases as a result of the economic attractiveness of the process, theresulting substitution would, of course, lead to a correspondingreduction in the consumption of primary resources.

Further advantages, features and details of the invention will beapparent from the following description of preferred embodiments andwith reference to the drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sketch of the process sequence for the breaking-up of acomposite element against a deflector wall with three steps;

FIG. 2 shows the transformation of the composite element fed to thedeflector wall in four stages;

FIG. 3 is a schematic top view of rotating deflector faces during theprocess;

FIG. 4 is a sketch showing a side view of a rotor;

FIG. 5 to FIG. 8 are process flow diagrams for different process steps.

DESCRIPTION OF EXAMPLE EMBODIMENTS

According to FIG. 1 a composite strip 10 of thickness e having a middlelayer 14 of an aluminium alloy covered on each side by PE layers 12 isfed in transport direction x to a deflector wall 20 crossing saidtransport direction. By virtue of the impulse due to acceleration and ofan abrupt cessation of this impulse against the deflector wall 20 andthe resulting shockwaves between the layers 12, 14 of the compositestrip 10, the physical differences of the different materials—such asthickness, elasticity, ductility and the like—are utilised in such a waythat, because of the different behaviour of the components 12, 14 of thecomposite strip 10, said components separate.

Through the impact against the deflector wall 20 materials liable todeformation—for example the aluminium layer 14—are deformed, whereaselastic materials—that is, the two plastics layers 12—absorb the impactenergy with the result that these PE layers 12 do not undergo any—oronly a slight—change to their structure. If a composite material 10 issubjected to such a treatment the metal layer 14 is deformed while theplastics layers 12 return after brief deformation to their originalstate through the restoring force. This different behaviour of thecomposite materials 12, 14 has the result that a shear force is producedbetween them which separates the layers 12, 14 along their phaseboundaries. In mixtures, breaking-up does not occur; however, because oftheir physical differences the materials present in the mixture alsotake on different structures. In this way—depending on theabove-mentioned physical properties—different characteristic structuresof the materials are produced.

Step b) in FIG. 1 shows the considerable and permanent deformation ofthe aluminium layer 14 and the very brief deformation of the twoplastics layers 12; a shear force is produced at the phase boundariesbetween the materials of the layers 12, 14.

In step c) of FIG. 1 both the aluminium layer 14—now in sphericalform—and the plastics layers 12 rebound against the impulse direction x,the plastics layers 12 having extended again from the deformationsituation of step b) as a result of the restoring force. Metals aredeformed and thereby attain a spherical structure which results from arolled-up metal layer 14; these spheres now have a diameter which is amultiple of the previous dimension in their planar structure prior totreatment.

The changes described are made clear in FIG. 2. Step a) shows theinitial product 10 with its strip-like layers 12, 14. In b) aprogressive breaking-up can be seen; the layers 12 gape apart and themiddle Al layer 14 is beginning to roll up in a tongue-like fashionagainst the impulse direction x. In step c) the middle layer 14 isadopting an increasingly spherical configuration and in step d) itreaches the spherical shape 14; the layers 12 have returned—as describedabove—to their original shape.

In the FIG. 3 deflector faces 24, 24 _(a), which are oriented towardsone another, project at a horizontal distance b apart from two wallfaces 22, 22 _(a) of parallel curvature and spaced apart by a clearradial distance a, one of the wall faces 22 rotating in direction yrelatively to the other wall face 22 _(a), and in the transportdirection x of composite materials 10. A line indicating an impactmotion of particles is denoted by z.

In FIG. 4 a rotor 26 with a direction of rotation y₁ about the rotoraxis A is indicated, to which rotor 26 a mixture of materials is fedfrom above at 30. The composite materials 10 of the mixture are directeddownwardly by gravity—the spiral transport path is indicated by 32.Introduced from below is process air the flow path 34 of which runscounter to the transport path 32. The dwell time of the compositematerials 10 in the rotor chamber 28 is influenced by the rising air andeasily dispersable particles and dusts are carried away in a cyclone andleave the rotor 26 with the process air at 36.

The energy recovery of the process can be seen from FIG. 5; not shownhere are the normal sequence steps during mechanical pre-treatment usinga bale opener—optionally in the form of a ball-type crusher—and a dryingstation, a pre-disintegrator, an Fe separator and a non-ferrousmaterials cutter. From the dryer, waste reaches a filter while usefulrecoverable materials are taken from the cutters to a mechanicalprocessing station. Arranged below the non-ferrous materials cutter is athermal recovery station for substances recoverable as energy (residualorganic material). The elements illustrated are a mixer or chargingdevice 40 ahead of a dosing device 42 followed by a station 44 forrotating-pipe gasification or fluidised bed combustion. This stationproduces slag or ash, as well as gas which is fed to a combustion boiler46. Steam flowing from the latter reaches a steam turbine 48 forgenerating electrical energy. Heat removed from the combustion boiler 46is fed to a mechanical pre-treatment process 50. In the lower area ofthis flow diagram it is indicated that the slag or ash from therotary-pipe gasification process 44 is fed through a discharge pipe 52to a KBS¹ process—used for manufacturing a ceramic or hydraulic binder;this is indicated in FIG. 6. Here additional materials are supplied in amixer or charging device 40 _(a). After mixing, dosing is carried out ina dosing device 42 _(a) from which the bulk material reaches a mill 54which produces hydraulic binder. ¹=ceramic binder system

In the mechanical processing stage according to FIG. 7 a disintegrator28 _(a) is followed by an Fe cutter 30 at the outlet 31 of which astation 36 _(a) for mechanical disintegration is located, which isfollowed by a non-ferrous materials cutter 32 _(a). At this stationnon-ferrous constituents and plastics constituents are separated on onehand and constituents recoverable in the form of energy on the other.The non-ferrous fractions are passed to a sifting station 58 having atable sorting device 16 from which the fractions of copper, light metaland various heavy metals are removed.

The plastics constituents from the non-ferrous materials cutter 32 _(a)reach a separator 62 which separates them into fractions of PE; PP; PS;PET and PVC. These substances are transported in each case tocompounding stations from which the corresponding granulate is removed.

FIG. 8 shows a process flow diagram for household waste. This waste issubjected as input material to mechanical pre-treatment at 64; usefulrecoverable materials such as metals, plastics mixtures and the like—inparticular heavy metals—pass through a discharge outlet 66 to amechanical processing station 70 which can also be reached by pre-sortedindustrial waste 69. Heavy metals are removed from the waste and slagquality material is produced as the starting product for hydraulicbinders.

Substances recoverable as energy are passed through a discharge outlet68 for further treatment. The fraction of useful recoverable materialsis processed mechanically and separated into up to four fractions,denoted by 71 (metals), 71 _(a) (plastics) and 71 _(b) (mineralsubstances). Also present is a fraction recoverable as energy which isconducted via the line 72 to this bulk material from the dischargeoutlet 68. The collected fraction of substances recoverable as energy istreated in station 74 by means of an energy process and the resultingthermal energy is fed back to the mechanical separation process at 76.

Slags and filtered dusts from the energy recovery process 74 reachstation 53 with the KBS process, from which a hydraulic binder isextracted.

1. A rotor configured to treat waste or recycled material, comprising; arotor housing having a center axis and configured to receive a material;an inner deflector wall within the rotor housing configured to rotateabout the center axis, wherein rotation of the deflector wall decomposesthe materials into components, the rotation of the deflector wall causesthe material to move in a substantially helical transport path in afirst direction; an outer deflector wall concentric with the innerdeflector wall and separated by a gap in which the material movesbetween the inner and outer deflector walls, the inner and outerdeflector walls each including at least one protrusion extendingtherefrom toward the gap and offset from one another, wherein thematerial decomposes upon striking the protrusions; and a port configuredto inject process air into the rotor housing, wherein the air moves in asubstantially helical airflow path in a second direction opposite to thefirst direction.
 2. The rotor of claim 1, wherein the material is acomposite having a metal component, wherein the metal component isdeformed into a substantially sphere-like shape upon being decomposed.3. The rotor of claim 1, wherein the material includes particlesentering the rotor housing are between and including 10 mm and 50 mm insize.
 4. The rotor of claim 1, wherein the first direction of thetransport path is downward and the second direction of the airflow pathis upward with respect to the rotor housing.
 5. The rotor of claim 1,wherein the process air expedites removal of the components from withinthe rotor housing.